1. Field of the Invention
This invention relates to optical connectors for connecting and/or fixing optical fiber ends or optical fiber cable ends to be used in optical communications and optical connector ferrules to be used therein, particularly optical connector ferrules having a metal tube incorporated therein as an integral part thereof (hereinafter referred to occasionally as xe2x80x9coptical connector ferrule of the metal tube built-in typexe2x80x9d). The term xe2x80x9cferrulexe2x80x9d used herein collectively refers to a capillary-shaped ferrule (also called xe2x80x9ccapillaryxe2x80x9d) and a ferrule having a flange part.
2. Description of the Prior Art
When an optical connector ferrule is connected to a semiconductor laser module to be used as a light source for an optical communication device and the like, a mount for attachment to a module is commonly used. Now, the relation between the ferrule and the mount is explained with reference to FIG. 1.
FIG. 1 illustrates one example of a conventional butterfly type LD module. An optical unit 20 assembled in advance is placed and fixed in a butterfly package 23. Reference numeral 24 denotes a group of package electrode terminals of the butterfly type which connect a driving power source to a laser diode (LD) 21 of the optical unit 20 and are adapted to be connected to electrode terminals of an optical system for monitoring the driving state. Two groups of electrode terminals 24 are respectively attached to both sidewalls of the package body as opposed to each other. A ferrule 1 into which a leading end of an optical fiber 2 is fitted is connected to the butterfly package 23 via a mount 10 for attachment to a module. Laser beams emitted from the laser diode 21 are collected by aspherical lenses 22 and 11 and introduced into the optical fiber 2 embedded in the ferrule 1 at the leading end thereof.
Heretofore, the ferrule 1 has been generally manufactured from ceramics such as zirconia and preliminarily press-fitted into the tube-shaped mount 10 made of stainless steel. This mount 10 is attached to the butterfly package 23 by laser welding. In the diagram the welding positions are indicated by the reference sign xe2x80x9cXxe2x80x9d.
Parts for optical connectors are required to have high dimensional accuracy in order to prevent the loss of light. The conventional method for the production of an optical connector ferrule (capillary) comprises the steps of first molding a ceramic powder containing a binder by injection molding, extrusion molding or the like thereby forming a ferrule blank, sintering the resultant blank, and finishing the blank into a desired dimension by subjecting it to machining such as abrasive finishing of the outside diameter, abrasive finishing of the inside diameter, and polishing of the leading end into the spherical convex surface (PC polishing). Since the inside diameter of a small hole of the ferrule for the insertion of an optical fiber is very small (for instance, the diameter of the small hole of the capillary of the SC type is 0.126 mm), the wire lapping finishing is commonly used for the finishing of the inside diameter thereof. Accordingly, the process of production is lengthy and requires expensive apparatuses such as an inside diameter finishing machine and an outside diameter finishing machine, and the cost of production is inevitably large.
In order to solve the problems mentioned above, the assignee of this application has already proposed to manufacture the ferrules from an amorphous alloy (Japanese Patent Application, KOKAI (Early Publication) No. 10-186176).
The use of amorphous alloy has such advantages that the ferrules satisfying the dimensional accuracy and the surface quality required of optical connector ferrules can be manufactured by a metal mold casting method with high mass productivity and in a single process and further that such machining steps as outside diameter finishing and inside diameter finishing of the ferrule can be diminished markedly. However, the weldability of an amorphous alloy to a metal such as stainless steel commonly used as a material of the mount 10 mentioned above is poor and thus the ferrule made of an amorphous alloy cannot be joined to the mount with sufficient strength. Therefore, it poses a problem that the ferrule made of an amorphous alloy can be used as a part of module only with difficulty.
It is, therefore, an object of the present invention to improve the joining properties or weldability of the ferrule made of an amorphous alloy and having excellent properties and advantages as mentioned above to a mount for attachment to a module and enable the ferrule to be used as a part of the module.
A further object of the present invention is to provide an optical connector ferrule having excellent optical properties, which ferrule can be joined or welded to a mount even when the mount made of a metal such as stainless steel is used and can be used as a part of the module.
To accomplish the objects mentioned above, a first aspect of the present invention provides an optical connector. A first embodiment thereof is directed to an optical connector comprising a mount having an accommodating portion or space and an optical connector ferrule attached to the mount, wherein the mount and at least the outer surface of the optical connector ferrule are made of the same kind of material and the ferrule is integrally joined to the mount. This embodiment includes the case that both the mount and the optical connector ferrule mentioned above are made of an amorphous alloy.
A second embodiment of the present invention is directed to an optical connector comprising a mount having an accommodating portion or space and an optical connector ferrule attached to the mount, wherein the optical connector ferrule comprises a body and a surface part covering the outer surface of the body, and the mount and the surface part mentioned above are made of the same kind of material and are integrally joined to each other.
Another aspect of the present invention provides an optical connector ferrule which can be advantageously used in this embodiment. The optical connector ferrule is characterized by comprising a body made of an amorphous alloy having at least a glass transition region and a surface part of an existing metal material covering the outer surface of the body.